Driving mechanism



Dec. 1, 1936. 1 T. PRITCHARD DRIVING MECHANISM Filed Jan. 5, 1934 3Sheets-Sheet 2' www@ 1 T. PRITCHARD 2,062,930 DRIVING MECHANISM Dec. 1,1936.

Filed Jan. 5, 1934 3 Sheets-Sheet 3 3 lE/// :E53/sii m m!i Patented Dec.l, 1936 UNITED STATES PATENT OFFICE 13 Claims.

The present invention relates to improvements in a driving mechanismand, more particularly, an overrunning or free wheeling drivingmechanism. In the present embodiment of the inven- 5 tion, it is shownapplied to an automobile drive.

However, it will be understood that the invention may be applied to anymechanism wherein an overrunning connection is desired.

The mechanism provided upon motor vehicles to permit overrunning or freewheeling driving is ordinarily constructed to provide a frictionalengagement of the driving and driven shafts or members when themechanism is in ordinary or noniree wheeling driving connection. Variousmechanisms for permitting the driving member to bepositively connectedto the drivenmemberwhen the two members are in driving relation haveheretofore been proposed, but none of these devices has been practical,primarily because it has been necessary for the driving and drivenmembers thereof to rotate through a considerable portion of a completerevolution with respect to each other in order to connect or disconnectthe same.

The principal'. object of the present invention is to provide anoverrunning drivingv mechanism arranged to permit the driving member tobe disconnected from the driven member when the speed of the drivenmember exceeds that of the driving member and adapted to positivelyconneet the driven member to the driving member when the speed'of thedriving member corresponds to or is greater than the speed of the drivenmember and with a. minimum amount of relative rotation between the twomembers to move a connecting member to or from driving engagementbetween the driving and driven members.

Another important object of the. invention is to provide a mechanism ofthe type described above wherein means is provided to cushion themovement of the connecting member to engaging position by hydraulicmeans, the hydraulically operated means being particularly constructedto contain a full supply of cushioning fluid during the operation of themechanism.

4;, Still another object of the invention is to provide a mechanism ofthe type described which is so constructed that it may be readilyincorporated into the driving mechanisms of motor vehicles providedLwith av drive. of the usual type. The relatively small size and theparticular construction of my invention, enables it to be installed in astandard clutch plate hub. The fact that my device is not of thefriction type drive and therefore has noI overrun drag, makes itparticularly adaptedto be assembled inthe clutch mechanism.

This installation eliminates the necessity of an extended housing on therear of the transmission, thereby permitting a straighter line drive tothe differential and eliminating the necessity of a lockout mechanismfor reverse drive. i

It is a further lobject of the invention to provide means, disposedentirely within the space occupied by the standard clutch throw-outsleeve, for rendering the overrunning clutch or free wheeling deviceinoperative.

Another important object of the invention is to provide. a mechanism ofthe type described which may be very readily and economicallymanufactured and assembled.

Other objects and advantages of the invention will be apparent from thefollowing specication and accompanying drawings, wherein:

Figure 1 is a view partly in central longitudinal section of a motorvehicle driving mechanism embodying the invention;

Figure 2 is a vertical sectional view taken on the line 2 2 of Figure 1;

Figure 3 is a vertical sectional view taken on the line 3-3 of Figure 1;

Figure 4 is a vertical sectional View taken on the line. 4-4 of Figure1;

Figure 5 is a vertical longitudinal sectional view through the clutchhub used in the present embodiment of the invention;

Figure 6 is a vertical sectional view taken on the line 6-6 of Figure 1;

Figure '7 is a view of the connecting member used in the presentinvention;

Figure 8 is a vertical sectional view taken on the line 8-8 of Figure 1;and

Figure 9 is a detail view of one ofthe elements of the structure of myinvention taken on` the line 9-9 of Figure 4.

In the drawings, my invention is shown applied to the driving mechanismlof a motor vehicle. With the description of the application of theinvention to a motor vehicle which is hereinafter. set forth, the modeof application of the invention to other forms of driving mechanism willbe entirely apparent.

The numeral I0 designates a transmission drive pinion shaft which willbe referred to in the present description as the driven shaft orelement. In accordance with the usual practice, the shaft I0 extendsinto a clutch casing II and carries a transmission drive pinion I2 atits outer end exteriorly of the casing. The inner end of the shaft I0 ismounted in the usual transmission drive pinion pilot bushing I3 of acrank shaft I4. 55

A clutch hub or rotatable element I5' is freely mounted for rotation onthe inner end of the shaft I0, the web I6 of the clutch plate extendingoutwardly from the hub I5. The clutch of which the clutch hub and webform a part is adapted to be actuated in the well known manner by meansof a clutch operating fork I1.

The shaft I0 is provided within the clutch hub I5 with spirallyextending teeth or threads I8 upon which is mounted a drive connectingmember or nut I9 provided on its interior surface with grooves to engagethe teeth I8. The outer surface of the connecting member or nut I9 isprovided with two sets of axially spaced annular rows of teeth 20. Theinner surface of the clutch hub I5 is also provided with two axiallyspaced annular rows of teeth 2I with which the teeth 20 on the nut I9are intended to engage when the mechanism is in driving connection. Theteeth 2U and 2I on the connecting member I9 and the clutch hub I5,respectively, extend substantially parallel to the teeth or threads I8on the shaft I 0, but are arranged at a somewhat different angle thanthe latter teeth. For example, the teeth or threads I8 on the shaft IIJmay be spiralled at an angle of approximately thirty degrees while theteeth on the outer surface of the connecting member I9 and the teethupon the cluch hub I5 may be spiralled at an angle of approximatelytwenty-five degrees.

As is shown in Figure 1, the teeth 20 on the connecting member I9 andthe teeth 2| on the :lutch hub I5 are so arranged with respect to eachother that when the teeth of the connecting member are disengaged fromthose of the clutch hub, the respective rows of teeth will be axiallystaggered, with the result that the connecting member need move but arelatively short distance to place the teeth thereof in full engagementwith the teeth of the clutch hub.

It will be understood that, if desirable, the number of rows of axiallyspaced teeth provided on the respective members may be increased inorder to increase the contacting surface area of r the teeth or tofurther expedite their engaging movement. In some instances, it may onlybe necessary to provide a single row of teeth upon each of the engagingelements. However, such an arrangement will slightly prolong theengaging movement of the teeth. Nevertheless, even if such a structureis provided, the provision of the spiralled teeth 20 and 2I will, as ishereinafter explained, enable the teeth to be more quickly engaged thanis the case in the usual device of this type.

In order to cushion the extreme inward movement of the connecting memberI9, that is, its movement to the left in Figure 1 of the drawings, ahydraulic cushioning means is provided. This means comprises an abutmentnut 22 threadedly connected to the shaft I0 and provided with an annulargroove or chamber 23 opening to its outer face 24. Ports 25 extend fromthe annular groove 23 to the peripheral surface of the nut 22 and maythere open into pockets 25a, as shown in Figure 2. The ports and pocketsare arranged at such an angle that rotation of the shaft I0 and nut 22will cause oil to be forced from the interior of the clutch hub I5,through the ports 25, into the annular groove or chamber 23. An annularprojection 26 is provided upon the inner end of the connecting member I9in alignment with the annular groove 23 of the nut 22. By thisarrangement, the movement of the connecting member I9 to the left, inFigure l, will cause the projection 26 to move into the groove 23. Sincethe ports 25 are located adjacent the outer end of the groove 23, inwardmovement of the projection 26 will cause these portsto be closed,preventing egress of oil from the groove except past the relativelyclose clearance between the walls of the projection and the walls of thegroove. In order to furnish an additional cushioning means, a coilspring 21 may be provided in the groove 23, although such a spring isnot usually necessary.

The outer end of the connecting member or nut I9 is tapered as indicatedat 39. A friction drag washer or ring 3I, shown in detail in Figure 8,is provided to bear upon the tapered surface 30. The friction drag ring3| is preferably formed of metal and has radially extending bent ears 32upon its periphery, which ears engage in longitudinally extendinggrooves 33 provided on the inner surface of the clutch hub I5, causingit to rotate with said clutch hub. A plurality of spring ngers 34, bentto generally conform to the outline of the tapered surface 30 of theconnecting member I9, exten-d inwardly from the ring 3| in order to holdthe same as closely as possible in contact with the tapered surface 38of the connecting member I 9. A coil spring 35 is positioned behind thering 3I with its inner end bearing upon the ring 3I and its outer end inengagement with a metal washer 36. A second metal washer 31 is spacedfrom the washer 36, with an oil packing washer 38 of suitable materialinterposed between the two metal washers.

An annular row 40 of teeth is provided upon the inner surface of the hubI5 at the outer end thereof and for a purpose subsequently explained.

In order to enable the friction drag washer or ring 3I to be insertedpast the row of teeth 48, the periphery of the ring 3I is provided withnotches 3Ia which are provided to .slip past the row of teeth 40. Themetal Washer 36 is preferably provided with similar notches in itsperipheral edge. The outer metal washer 31 is,

as shown in Figure 6, provided with notches 31a to permit it to beinserted past the row of teeth 40. 'I'he notches 31a .are spaced .aparta distance equal to that of the spacing between the teeth in the row 40and equi-distantly spaced between each pair of these notches, is arecess or ldepression 4 I. When the ring 31 has been inserted past therow of teeth 40, it is given a slight turning movement against theaction of the spring 35 to bring the recesses 4I into alignment with oragainst the inner ends of the teeth 40. The spring 35 will then exertsuflicient pressure, through the washer 36 and packing 38, to hold therecesses 4I of the ring 31 engaged against the inner ends of the teeth40 to hold the washer 31 in proper position and cause the entire packingstructure to be held in proper lateral .alignment and to turn with thehub I5.

As is shown in Figures 1 and '7, the connecting member or nut I9 may beprovided with oil ports 42 extending from its inner end I9a and withinthe shoulder 26 to pockets 43 on the peripheral .surface of the memberI9 between the rows oi teeth 20. By means of the ports 42, rotation ofthe member I9 will cause oil to be forced through the pockets 43 andports 42 to the threaded portion I8 of the shaft I0, thereby insuringthe lubrication of this portion of the shaft for rotation of the memberI9 upon the same.

The operation of the structure heretofore de- .iaocacco scribedis rasfollows: When the speed of rotation of the motor vehicle engine or other'sourcepf power, and therefore of the clutch hub I5, is equal to orexceeds that of the shaft I9, the connecting member or nut I9 willtravel on the threads'l'of the shaft I9 to the-left (Figure l). Thismovement is assured by two factors. First, the friction drag between thefriction drag washer or ring 3|, rotating with the clutch hub I5, andthe connecting member I9, gives the connecting member a positivefrictional tendency to rotate with clutch hub I5, thereby causing it toscrew` itself upon the threads I8, entirely independent of inertia ormomentum yinto positive driving engagement with clutch hub I5. Second,the spring 35, being of the compression type, together with the dragwasher 3|, tends to push theconnecting member ornut toward the left orengagement limit. Movement of the connecting member I9 to the left will'cause the rows of teeth 29 thereon to respectively engage the'rows ofteeth 2| on the'clutch hub I5, thereby'connecting the shaft I9 to theclutch hub I5 by a positive driving means.

Because of the fact that teeth 29 and'2I are spiral, instead of beinglongitudinally parallel with the axis of the shaft I9, the movement' ofthe connecting member I9 into engagement with the teeth 2| on the clutchhub I5 will be greatly expedited, the connecting member I 9 being givena bodily rotational movement in the same direction as that of the'direction of rotation of the shaft I9 and clutch hub I5but at a fasterspeed,

due to the inclination ofthe teeth, until the connecting member I9 'is'fully engaged with the clutch hub I5.

The movement of the connecting'member I9 to place the teeth 29 in fullengagement' with the teeth 2| upon the clutch hub, will also beexpedited by reason of the fact that `both rows of teeth areaxiallyspaced and that the' teeth, when in disengaged position, are axiallystaggered. That is to say, because ofthe axial staggering of the rows ofteeth of therespective members, the connecting member I9'need -onlymove'onehalf the axial distance to obtain full engagement which would benecessary in `teeth of a. like area and where the two sets of teeth areformed in single rows.

When the connecting member I9 travels to the left to effect a drivingengagement between the teeth, there is ordinarily a likelihood of theoccurrence of a shock or jar when the connecting member reaches the endof its movement and a positive connection is established. However, bythe provision of the fluid cushionmeans comprising the annular groove 23and the projection 26, all possibility of such a shock or jar iseliminated. The-provision of the spring 21 in the grooves 23, ifnecessary, also assists in preventing anyshock.

When the speed of rotation of the shaft I9 or elements connectedtherewith exceeds that of the source of power, and therefore the 'clutchhub I5, the increased rotation of the shaft will cause the connectingmember I9 to move to the right, that is, to the position showninFigure 1. 'Such movement will `be against theaction of the friotiondrag ring 3| and its associated spring 35 and will result in thedisengagement of the teeth 29 upon the connecting member from the teeth2|- within the clutch hub. The friction 'drag between the ring 3| andthe connecting'member I9 will tend to retard the rotation `of'theconnecting member I9 with respect to' the'shaft I9 and, as'aconsequence, thereH will "be-.a 'positive frictional member I9.

rbehind the teeth 52. 55, fixed to the casing II, there is positioned asleeve 51 r(Figures 4 and 9) which includes an "armiGZa onthe shaft 93and fdash'ofthe vehicle.

tendency forfthe connecting member '.to turn .upon the threads I8 to theright and 'out ofengagement with the teeth 2|. So long as the shaft I9is over-running the clutch hub I5, this tendency -will be 'present andthere will be no driving connection between the shaft and the source ofpower.

If-'a spring such as 21 is provided in the annular groove 23 of theabutment nut 22, such a spring will urge theconnecting member I9 to theright i 'when the spring 21 is compressed and this spring of means toenable the shaft I9 to be locked intoa positive bi-directional drivingconnection with the clutch hub I5 or other source of power. This meanscomprises a toothed collar 59 slidable upon splines I9a upon the shaftI9 and adjacent the outer end of the clutch hub |5.

lBy movement of the collar 59 to the left into engagement with the teeth49 formed upon the interior of the outer end of the clutch hub I5, theshaft I9 will be locked to the 'clutch hub I5, regardless of theposition of the connecting To effect a very ready engagement of the`teeth'52 upon the collar 59 with the teeth 49, alternate teeth of theteeth 52 upon the collar may be cut back on their inner ends-asindicatedat 53. Also, the number of teeth 49 within the clutch hub I5,is but half that upon the collar 59. By this well known arrangement,movement of the collar 59 to the left results in readier engagementwiththe teeth 49, while the vshaft I9 or clutch hub I5 are rotating.

The collar 59 is provided with a circumferential groove 55 in its outersurface-and directly Within the quill or sleeve arcuate' extensionl 58at its inner end provided with an internal shoulder 59 which engages inthe'groove 55 of the collar 59. The sleeve 51 is provided with an arm-99projecting through a slot 6| in the quill 56, which arm is engaged byone'arm `of a bell crank lever 62 mounted v'to rock upon a shaft-63extending across ano journaled in the clutch housing II. A manuallyoperated connection 54 is secured to anrouter v, l-yspring pressed ballS1 is positioned in a 'socket inthe shaft I9 .and the surface of thebore of the collar 59 is provided with two axially spaced sockets 58, inone of which the ball .Gl will` bexseated in each positionof the collar59.

"Itisdesirableto form the. sockets 68 in two circumferential rows, eachVindividual socket alternating fwith .the splined grooves in the bore ofthe collar, since, by this arrangement. regardless of thecircumferential position of the collar on the shaft I9,` a pair ofsockets AISS will be axially alignedwith the ball 51.

It will be observed by this arrangement, the

cclar^59 may be moved into or out of connection `withthe teeth 49 of theclutch'hub I5 regardless of the position of the connecting member `I9.The arrangement of the shoulder 59 in `the groove-55 permits collar 59to rotate Yfreely v-witlrrespect lto vthe shoulder.

if the spring 21 is not i extends to the It will be observed that myinvention provides for particular relative alignment or timing of thespiral` teeth or threads I8 on the shaft I0 with respect to the straightsplines Illa on the shaft I0, upon which the collar 50 travels. By thisalignment, together with proper timing of the teeth on the connectingmember I9, inside and out, the teeth on collar D, inside and out, andthe teeth on the inside of the clutch hub, a complete timing result isaccomplished, thereby automatically creating the positive alignment ofall the teeth, when in driving position, which permits the locking outof free-wheeling, without feeling for mesh.

The number of external teeth 20 on the connecting member I9 must be thesame or a multiple of the internal teeth thereon, which latter mesh withthe threads I8 on the shaft I0.

This alignment is to be made at the lead, on the driving or right-handend of the spiral thread on the shaft. For instance, should one look;from the driving end, the leads of all the threads and splines would bein straight diametrical and longitudinal alignment.

It will also be noted that I provide a device wherein when the hubattempts to overrun the RIJ shaft, a frictional means which tends torotate a connecting member faster than the shaft, causes the connectingmember to travel to the left in Figure 1 toward its driving orengagement limit. This construction also insures that when the shaftoverruns the hub, this same frictional means tends to hold theconnecting member at a lower rate of speed than the shaft, therebycausing the connecting member to return to its disengaging limit,because of its spiral thread connection with the shaft.

Means is also provided to accomplish an automatic alignment of the teethon the clutch hub and the teeth on the lockout collar, when theconnecting member is in driving position. This arrangement permits thelocking-out of freewheeling without feeling for mesh, as is necessarywith all present units.

It will be understood that the invention is not limited to the detailsof construction shown in the drawings and described in the specicationand that the examples of the use of the device which have been given donot include all of the uses of which the device is cap-able; also, thatthe phraseology employed in the specification is for the purpose ofdescription and not of limitation.

I claim:

l. The combination of a rotatable shaft element, an element rotatablewith respect to said shaft element, a drive connecting member, means onone of said elements to move said member to connect said elements indriving relation in accordance with the difference in speed of rotationof said respective elements, said means being so arranged with respectto said rotatable elements as to move said member into drive connectingrelation with a bodily rotational movement faster than that of saidshaft element.

2. he combination of a rotatable shaft element, an element rotatablewith respect to said shaft element, a drive connecting member, means onone of said elements to move said member to connect said elements indriving relation in accordance with the difference in speed of rotationof said respective elements, said means being so arranged with respectto said rotatable elements as to move said member` into drive connectingrelation by a bodily circumferential and linear movement with respect tothe axis of said elements, such circumferential movement of said memberbeing in the same direction as the rotational movement of said elements.

'3. The combination of a rotatable shaft, a member rotatable on saidshaft, said shaft being provided with a thread, a connecting memberengaging said thread, said first member being provided with spirallyextending teeth arranged at an angle different from that of the angleof` said thread, and said connecting member being provided with teethadapted to engage the teeth on said rst member, said connecting memberbeing adapted to be moved with respect to said first member inaccordance with the difference,

extending teeth to cause said connecting member to move into engagementwith said first member circumferentially with respect to said shaft andin the same direction as the direction of rotation of the latter.

5. The combination with a rotatable shaft, a:

member rotatably mounted on said shaft, a connecting member mounted onsaid shaft and adapted to be moved to connect said shaft and said firstmember in accordance with the difference in speed of rotation of saidshaft and saidlr first member, of a hydraulic cushioning means to resistinward movement of said connecting member with respect to said firstmember comprising a chamber in one of said members, means to force acushioning fluid into said chamber and means,I

on the other of said members to close said iiuid supply chamber againstegress of fluid therefrom upon the inward movement of one of saidmembers with respect to the other.

6.The combination of a rotatable shaft, ay

member rotatable on said shaft, a connecting member threaded on saidshaft to connect said first member and said shaft in accordance with thedifference in speed of rotation of said first member and said shaft,said first member andk said connecting member being respectivelyprovided with axially spaced sets of teeth, the respective axiallyspaced sets of teeth on said members being in axially staggered relationwhen in disengaged position.

f?. The combination of a rotatable shaft, a member rotatable on saidshaft, a connecting member threaded on said shaft to connect said firstmember and said shaft in accordance with the difference in speed ofrotation of said first4 member and said shaft, said first member andsaid connecting member being respectively provided With axially spacedsets of spirally arranged teeth to cause said connecting member to moveinto engagement with said first member circumferentially of said shaftand in the same direction as the direction of rotation of the latter,the respective axially spaced sets of teeth on said members being inaxially staggered relation when in disengaged position.

8. The combination of a rotatable shaft, a member rotatable on saidshaft, 'a connecting member threaded on said shaft to connect said firstmember and said shaft in accordance with the difference in speed ofrotation of said first 76 member and said shaft, said rst member andsaid connecting member being respectively provided with spirallyarranged teeth, a second set of teeth on said first member, and atoothed member slidable on said shaft to connect said shaft and saidfirst member regardless of the position of said connecting member.

9. The combination of a rotatable shaft, a driving clutch hub mounted toturn freely about the axis of said shaft and provided interiorly withtwo annular sets of teeth in longitudinal alignment, a nut having innerand outer teeth in diametrical alignment engaging a thread on the shaftwithin the clutch hub and p-rovided with teeth adapted to mesh with oneset of teeth on the clutch hub, a spring mounted to rotate with the huband acting to effect engagement of one of said sets of teeth and the nutand to permit disengagement of such teeth when the speed of rotation ofthe shaft exceeds that of the clutch hub, a toothed member splined tothe shaft and adapted to mesh with the second set of annular teeth onthe clutch hub, a member extending longitudinally of the shaft andadapted to position said toothed member in engagement with or at oneside of the coacting teeth on the clutch hub, and means forautomatically locking said toothed member in either of said positions.

10. The combination of a rotatable shaft, a driving clutch having itshub mounted to turn freely about the axis of said shaft and providedwith two sets of annular teeth, a nut engaging a thread on the shaft andprovided with teeth adapted to mesh with one of the sets of annularteeth of the clutch hub, a spring engaging a frictional drag washerslidably mounted to rotate with the hub, said spring forcinglongitudinal movement of the washer into frictional engagement with saidnut tending to cause said nut to rotate with the hub, forming the meansto effect an engagement of said teeth on the nut and hub, and to permitdisengagement thereof when the speed of rotation of the shaft exceedsthat of the clutch hub, a toothed member splined to the shaft, and amember for moving said toothed member to effect engagement of the teeththereof with the second annular set of teeth on said clutch hub.

11. The combination of a rotatable shaft, having two sets of teeththereon, each set having the same number of teeth, the teeth of one ofsaid sets being parallel with the axis of the shaft and the teeth of theother set being spiral, said sets of teeth being in diametrical andlongitudinal alignment, a driving clutch hub provided with two sets ofteeth, each set of the same number as the number in one of said sets onsaid shaft or a multiple thereof, said hub being mounted toturn freelyabout the axis of said shaft, a connecting member having inner and outerteeth in diametrical alignment, said inner teeth engaging the spiralteeth on said shaft and the said outer teeth being adapted to mesh withone of the sets of teeth on said clutch hub, and a member having innerand outer teeth in diametrical alignment, said inner set of teethengaging the axially extending teeth of said rotatable shaft and saidouter teeth being adapted to mesh with the second set of teeth on saidclutch hub, and means to selectively engage said last named member withthe teeth on the clutch hub.

l2. The combination of a rotatable shaft, a member rotatable on saidshaft, a connecting member threaded on said shaft to connect said firstmember and shaft in accordance with the difference in speed of rotationof said first member and shaft, said first member and said connectingmember being respectively provided with spirally extending teeth tocause said connecting member to move into engagement with said firstmember circumferentially With respect to said shaft and at a fasterbodily rotation than that of said shaft.

13. The combination of a rotatable shaft, a toothed driving clutch hubmounted to turn freely about the axis of said shaft, a nut includingteeth engaging a thread on the shaft, a frictional drag washer slidablymounted to rotate with the hub, a spring to longitudinally force saidwasher into frictional engagement with said nut, tending to cause saidnut to rotate with the hub to effect an engagement of said teeth on thenut and hub and to permit disengagement thereof when the speed ofrotation of the shaft exceeds that of the clutch hub, and manuallyoperable means for effecting positive engagement between the shaft andclutch hub independent of said nut.

LEVI THOMAS PRITCHARD.

